Current 3GPP standards include functionality to apply usage monitoring for accumulated usage of network resources per IP Connectivity Access Network (IP-CAN) session, per user or per service basis. In particular, the usage monitoring is carried out by a Policy and Charging Control (PCC) architecture including a Policy and Charging Enforcement Function (PCEF) in charge of traffic flow detection and enforcement of applicable policies to user traffic flows; and including a Policy and Charging Rules Function (PCRF) in charge of providing network control for the traffic flow detection by holding policies and providing PCC rules to the PCEF per user traffic flow basis for enforcement of such policies. Moreover, the usage monitoring is thus applicable for service data flows associated with both predefined PCC rules and dynamic PCC rules.
At present, the usage monitoring function is used to control the usage of network resources by subscribers during a period of time, for instance, in order to control a certain amount of volume usage per period of time. This period of time is generally known as reporting period and set to one month.
In particular, the usage monitoring function is applicable for an individual service data flow, a group of services data flows, or for all traffic of an IP-CAN session. Usage monitoring function is thus applicable for service data flows associated with both predefined PCC rules and dynamic PCC rules.
Conventionally, the PCRF is enabled to obtain information about the usage per user at the end of the reporting period and to provide new usage limits allowed for a new reporting period of time.
To this end, the PCRF makes dynamic policy decisions for usage monitoring and sends applicable volume thresholds to the PCEF for monitoring, whereas the PCEF notifies the PCRF when a threshold is reached and reports the accumulated usage since the last report for usage monitoring. The usage monitoring thresholds are traditionally based on volume. Then, the PCRF makes new policy decisions based on the accumulated usage when a specific threshold has been surpassed and provides the PCEF with these new policy decisions, for example downgrading the quality of service.
With the current use of the usage monitoring function per reporting period, the end of the reporting periods is generally set at the same time for a large number of subscribers, thus causing a huge signalling peak over the so-called Gx interface between PCRF and PCEF when this occurs.
On the other hand, in a scenario in which the control of usage is done during the reporting period, when the usage reported for a subscriber exceeds a usage limit permitted in the PCRF, the PCRF indicates towards the PCEF a new policy decision that needs to be enforced. This may be a new quality of service profile, the denial to access to certain services, etc. Then, when the reporting period expires, the PCRF needs to re-evaluate the policy rules and indicate to the PCEF the new policy decision that needs to be enforced.
As exemplary shown in FIG. 5 for a subscriber, the subscriber has a volume limit for the month, which in the example is surpassed before the end of January; the policy decision taken by the PCRF is to downgrade the quality of service to 256 Kbps (previously to the surpassed limit, the Maximum bit rate was 1 Mbps). When the end of the period is reached and a new reporting period begins the usage counters need to be reset and the policy decision needs to be re-established.
A conventional solution nowadays requires that the PCRF sends a message to the PCEF, when the end of the reporting period is reached, in order to request the accumulated usage and to provide a new policy decision. Since the end of the reporting period is the same for a huge amount of subscribers, this conventional solution has the problem mentioned before of signalling storms at the end of the reporting period for a large number of subscribers.